1. Field of the Invention
The present invention relates generally to a channel state information transmission/reception method and apparatus and, more particularly, to a method and apparatus for transmitting and receiving channel state information in a wireless communication system supporting a plurality of antennas.
2. Description of the Related Art
A Reference Signal (RS) is used to measure the channel state (or quality) between a base station and users (such as, for example, signal strength and distortion, interference strength, and Gaussian noise), and is used in demodulation and decoding of a received data symbol in a wireless mobile communication system. The reference signal is also to measure a radio channel state. The receiver measures the strength of the reference signal transmitted by the transmitter at a predetermined transmit power to determine the radio channel state between the receiver and the transmitter. The receiver sends a request to the transmitter for a data rate based on the determined radio channel state.
The 3rd generation evolved mobile communication standards such as, for example, the 3rd Generation Partnership Project Long Term Evolution-Advanced (3GPP LTE-A) and Institute of Electrical and Electronics Engineers (IEEE) 802.16m, adopt a multi-carrier multiple access technique such as Orthogonal Frequency Division Multiplexing (Multiple Access) (OFDM(A)). In the case of a multi-carrier multiple access-based wireless mobile communication system, the channel estimation and measurement performance is influenced by the number of symbols and the number of subcarriers to which the reference signal is mapped on the time-frequency resource grid. The channel estimation and measurement performance is also influenced by the power allocated for reference signal transmission. Accordingly, by allocating more radio resources (including time, frequency, and power), it is possible to improve channel estimation and measurement performance, resulting in improved received data symbol demodulation and decoding performance and channel state measurement accuracy.
In a resource-constrained mobile communication system, however, if the radio resource is allocated for transmitting resource signals, the resource amount for data signal transmission is reduced. For this reason, the resource amount for the reference signal transmission is determined by taking the system throughput into account. Particularly, in a Multiple Input Multiple Output (MIMO) system including a plurality of antennas, a key issue is how to design and measure reference signals.